The objective of the proposed research project is to examine the biobehavioral hypothesis relating chromosome changes to impaired mental functioning in the elderly. Specifically, to determine whether or not hypodioploidy and/or other chromosome changes occur more frequently in glial cells of patients with senile dementia of the Alzheimer type than in those without senile dementia, and to correlate glial cell findings with findings in peripheral lymphocytes. Human brain tissue and blood samples for culturing and chromosome examination will be obtained at autopsy. Most of the first year has been spent in perfecting glial cell culture techniques, chromosome preparation procedures, and cell identification methods. Two groups of subjects will be evaluated, elderly patients 65 years and older with senile dementia and younger patients less than 40 years of age without dementia. Comparison between these two groups will maximize the likelihood of detecting chromosome changes and constitutes an important first step in assessing whether or not chromosome change is a biological factor which may underlie senile mental changes. It is only when biological factors which contribute to functional deficits can be identified that the observed functional changes will become more understandable and eventually treatable.